Biocompatible and biodegradable aromatic polyanhydrides are disclosed by U.S. Pat. Nos. 4,757,128 and 4,997,904. However, unless incorporated into a copolymer containing a more hydrophilic monomer, such as sebacic acid, the aromatic polyanhydrides of the prior art have slow degradation times as well as relatively insoluble degradation products. A major drawback to the prior art aromatic polyanhydrides is their insolubility in most organic solvents.
Biocompatible and biodegradable aromatic polyanhydrides prepared from para-substituted bis-aromatic dicarboxylic acids are disclosed by U.S. Pat. No. 5,264,540. The para-substitution pattern results in higher melt and glass transition temperatures and decreased solubility, thus ultimately making these para-substituted polymers difficult to process.
A need exists for biocompatible and biodegradable aromatic polyanhydrides having improved degradation and processing properties, as well as therapeutic utilities.